This application claims the benefit of Japanese Patent Application No. 10-361921, filed Dec. 4, 1998, which is hereby incorporated by reference.
1. Field of the Invention
This invention relates to speaker devices, and more particularly, to speaker devices for conversion of electrical signals into corresponding acoustic energies and the associated method for manufacturing such speaker devices.
2. Discussion of the Related Art
FIG. 6 illustrates the arrangement of an electrically-driven cone-shaped speaker of the conventional art. This traditional cone-shaped speaker unit of FIG. 6 is designed to include, for example, a vibrator plate 1, formed of part of a nearly conical shape, and a cylindrical voice coil bobbin 3 with a voice coil 2 wound there around as laid out at the center of the vibrator plate 1 in a manner such that these elements are integral with the vibrator plate 1.
The vibrator plate 1 and voice coil bobbin 3 are rigidly attached to a ring-shaped edge portion 8, having appropriate compliance and stiffness, and also to one terminate end of a dumper 9. Moreover, the edge portion 8 and a remaining end of the dumper 9 are fixed to a frame 12 that is integrally formed with a magnetic circuit 7 thereby attaining elastic support of the vibrator plate 1 and voice coil bobbin 3 together.
With such an arrangement, the edge portion 8 and dumper 9 serve to dispose the voice coil 2 and voice coil bobbin 3 within a magnetic gap of the magnetic circuit 7 that consists essentially of a magnet 4, a plate 5, and a pole yoke 6, for example, in such a mariner that the voice coil 2 and bobbin 3 are not in physical contact with the magnetic circuit 7. The vibrator plate 1 is situated to be elastically supported so that it offers reciprocal piston-like vibrating abilities within a predefined vibration range in a specified direction.
In addition, both ends of the voice coil 2 are connected to selected ends of a pair of conductive lead wires 11 respectively, the remaining ends of which are connected to a pair of terminals 10 as provided at the frame 12, respectively.
This arrangement results in the voice coil 2 operating responsively to the receipt of electrical drive power as supplied thereto from the terminals 10 via the conductive lead wires 11 for producing magnetic flux. The voice coil 2 is thus driven within the magnetic gap of the magnetic circuit 7 in a direction along the piston vibration direction of the vibrator plate 1. The vibrator plate 1 vibrates in a manner that is integral with the voice coil 2 and voice coil bobbin 3 to convert electrical signals into corresponding acoustic energies for external radiation of resultant sound waves.
The arrangement of related art results in several inherent problems. For example, the voice coil 2 increases in temperature with an increase in drive power due to the fact that the electrical energy input to the voice coil 2 will possibly be converted not only to the externally radiated acoustic energy stated above, but also to energy consumed by resistance components of the voice coil 2 and the like. This temperature increase results in the occurrence of various damages of coatings and distortion due to thermal expansion of the voice coil 2 as well as unwanted breakdown, or open-circuiting, of lead wires used. This in turn leads to an eventual destruction of the speaker unit.
Because the cylindrically-shaped voice coil 2 of the related art is arranged so that the magnetic circuit 7 surrounds the periphery of the coil 2 in a manner such that the magnetic circuit 7 spatially sandwiches it at both surfaces thereof with a predetermined narrow gap retained therebetween, heat generated from the voice coil 2 must be released toward the outside in order to reduce temperature within the speaker arrangement based on a flow of the air residing in this narrow gap, carrying the heat as shown in FIG. 7. The heated air then attempts to move or xe2x80x9cdriftxe2x80x9d due to vibrations at the voice coil 2 and also heat conduction toward the magnetic circuit 7. This results in an eventual cooling of the voice coil 2 to reduce its temperature. However, such a heat release/radiation scheme utilizing air as a heat-carrying medium remains lower in efficiency of conduction of heat of the voice coil 2 so that the drive power will be likewise lowered in critical level leading to eventual destruction of the speaker. This simultaneously limits or restricts the input durability of the speaker per se. In view of these problems, a key to effective speaker design lies in the minimization of voice coil 2 temperature increases due to drive power while at the same time maximizing the input durability of the speaker itself.
One prior art attempt to remedy the temperature increase problem discussed above is to employ specific structural members made of thermal-resistant materials and/or to redesign the speaker device structure. These prior approaches nevertheless do not attain the intended effects of solving the above-described problems.
Accordingly, the present invention is directed to a speaker device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is the provision of a speaker device that results in a improved flow of heat generated within the speaker device to the outside of the speaker device.
Another object of the present invention is to improve the cooling effects of the speaker device and increasing the heat release efficiency of the voice coil within the speaker device to thereby enhance the input durability of the speaker device.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the speaker device includes an voice coil having a thermal radiator layer provided on a surface of the voice coil. This thermal radiator layer is made of a chosen heat-releasable material for use in emitting radiant energy including infrared rays.
In another aspect of the instant invention, the speaker device includes a voice coil and a radiant layer made of a radiant energy emissive material provided on a surface of the voice coil.
In a further aspect of the instant invention, a method of manufacturing a speaker device comprises the steps of providing a voice coil within the speaker device; forming a radiant layer from a radiant energy emissive material; and providing the radiant layer on a surface of the voice coil.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.